"use strict";
let a = null;
let b = undefined;
console.log(a, b);
function show() {
    return true;
}
console.log(show());
let str = "abc";
// str = undefined;
// str = null;
// 任何一个数据类型都可以把undefined和null赋值给它，如果不允许，把"strictNullChecks": true打开
console.log(str);
